Surgical trocars having optical tips defining one or more viewing ports

ABSTRACT

A trocar obturator includes a hollow tube having a substantially solid, optically clear tip attached thereto. A distal cutting end of the tip is formed by a pair of opposing, angularly oriented surfaces which converge to a line at that point with a cutting element disposed along the line. For electrosurgical operation, an electrode is positioned along the line. The tip serves as a viewing window and defines a viewing port at its proximal end for an endoscope inserted into the hollow obturator tube for viewing a tissue wall as it is penetrated. The trocar obturator tip may include an axial bore extending between its proximal and distal ends with a viewing rod within the bore for viewing the area ahead of the tip. Here again, the distal cutting end of the tip may be formed by a pair of opposing angularly oriented surfaces which converge to a line. Two cutting elements extend linearly along the distal end of the tip, one on either side of the bore. For electrosurgical operation of the obturator, the cutting elements comprise electrodes. The distal end of the viewing rod may also be formed by a pair of opposing angularly oriented surfaces which converge to a line at its distal end. For best results, particularly with electrosurgical cutting, the distal end of the viewing rod extends slightly beyond the distal cutting end of the tip.

BACKGROUND OF THE INVENTION

The present invention relates in general to surgical instruments whichare used to puncture tissue walls for the performance of endoscopicsurgery within body cavities, organs, joints and the like covered by thetissue walls and, more particularly, to such surgical instruments ortrocars which permit viewing the tissue walls during wall puncturingoperations to help prevent injury to structures within the tissue wallsand fields of operation beyond the tissue walls.

Endoscopic surgical procedures have become widely accepted. Theseprocedures permit surgeons to employ a wide variety of endoscopicinstruments with minimal incisions into the skin and tissue surroundinga body cavity or other targeted interior surgical site. In order tointroduce these endoscopic surgical instruments into an interiorsurgical site, it is necessary to first puncture and cannulate the siteusing an initial surgical instrument known as a trocar.

Conventional trocars consist of a trocar obturator and a trocar cannula.A manual obturator may have a sharp pointed end which serves to piercebody tissue and to widen the resulting opening to the width of theobturator and cannula which is carried along with the obturator.Alternately, while still piercing body tissue and widening the resultingopening, a radio frequency (rf) obturator may have one or moreelectrodes associated with its distal end such that rf energy can beapplied to the electrodes and effect tissue cutting.

In either event, the insertion of a trocar, particularly a first trocar,even with the skilled selection of a penetration site, involves a riskof damaging blood vessels at the site. There is further risk of damageto vessels, organs and other interior structures after penetration ofthe tissue wall. In the case of the abdomen, the small intestine andomentum majus are especially at risk if adhesions and concretions withthe anterior abdominal wall are present since during penetration of theabdominal wall, structures adhering thereto may be pierced before thetrocar enters free abdominal space.

To reduce the risk of damage, particularly to the intestine and omentummajus, a hollow needle can be passed through the abdominal wall whilethe abdominal wall is lifted to introduce gas into the abdominal cavityand thereby extend the abdominal wall away from the underlying omentummajus and intestine for insertion of a trocar. Even then there isresidual risk of damage during insertion of the hollow needle andtrocar.

While trocars must be capable of penetrating tissue walls to cannulate atargeted surgical site, a variety of safety trocars have been developedwhich serve to protect vessels, organs and other structures within abody cavity. For example, a spring-loaded shield may be associated withthe cutting tip of a manual obturator such that the shield springsforward to shield the cutting tip as soon as the tip penetrates a tissuewall.

A second approach to protecting against damage which can be done bytrocar insertion is to associate optics with a trocar such thatinsertion of the trocar can be guided based on images of the penetrationsite. Optics are disclosed for use in a manual trocar obturator inpublished European Patent Application No. 0484725 A1.

The trocar disclosed in the noted European Patent Application includes ahollow shaft which terminates in a hollow conical window. An optic isinserted down the hollow shaft and terminates at an axial distance fromthe summit or point of the hollow conical window such that the entirewindow can be illuminated and viewed by the optic. A second optic may berun laterally passed the first optic to a window-forming point at thesummit or point of the conical window such that the advance of thetrocar can be viewed. The first and second optics are disclosed aspreferably being wide-angle or fish-eye optics. If both optics areprovided, the operator can obtain a feeling for the path and rate ofadvance, and also observe the structures lying in front of the point toavoid damage as the trocar is inserted.

Optics are disclosed for use in a rf trocar in U.S. Pat. No. 5,221,281wherein a longitudinal circular channel is formed in an electrosurgicaltubular trocar through which an optical catheter can be passed. Thetubular trocar includes an electrode and a conductor at its distal endfor bipolar operation of the trocar.

Provision of a fiber optical cable in a trocar obturator is suggested inInternational Patent Application No. PCT/US92/01225. However, thestructure of this obturator is unclear since the specification refers toreference numerals and structure which is not shown in correspondingdrawings.

Since the view provided by the hollow optical window in the notedEuropean Patent Application may be distorted and the electrosurgicalcutting operation may interfere with the view provided by the opticalcatheter of the '281 patent, there is a need for surgical apparatus forinserting a cannula through tissue defining a wall of a body cavitywhich reduces the risk of possible damage to vessels, organs and thelike via improved optic control of the apparatus.

SUMMARY OF THE INVENTION

This need is met by the invention of the present application wherein, inits broadest aspect, a trocar obturator including a hollow tube having asubstantially solid, optically clear tip attached thereto is used toinsert a cannula through a tissue wall of a body cavity. Since thetrocar of the present invention can be used in a wide variety ofendoscopic operations, the term "body cavity" is used herein toencompass all appropriate structures including organs, joints and otherbody structures which must be cannulated for performance of endoscopicsurgery.

The distal cutting end of the tip preferably is formed by a pair ofopposing angularly oriented surfaces which converge to a line at thedistal end of the tip. A cutting element is disposed along the line forthis form of tip. For electrosurgical operation of the obturator, anelectrode is positioned along the line formed by the convergingsurfaces. The substantially solid, optically clear tip serves as aviewing window and defines a viewing port at its proximal end forpresenting images of tissue adjacent its distal end. Thus, aconventional endoscope can be inserted coaxially into the hollow tube ofthe trocar obturator to a point adjacent the viewing port for viewingthe tissue wall as the trocar is inserted therethrough.

In one embodiment of the invention, the trocar obturator tip includes anaxial bore extending from its proximal end to its distal end with aviewing rod positioned within the bore. For this embodiment, the area infront of the tip can be viewed via the viewing rod through an endoscopeinserted into the hollow tube of the obturator.

The distal cutting end of the tip may be formed by a pair of opposingangularly oriented surfaces which converge to a line at the distal endof the tip. Two cutting elements extend along the distal end of the tip,one on either side of the bore. For electrosurgical operation of theobturator, the cutting elements comprise electrodes. For thisembodiment, the distal end of the view rod is preferably also formed bya pair of opposing angularly oriented surfaces which converge to a lineat the distal end of the viewing rod. For best results, particularlywith electrosurgical cutting, the distal end of the viewing rod extendsbeyond the distal cutting end of the tip such that the tissue next to bepenetrated or internal structure ahead of the obturator tip can beimaged in spite of the otherwise disruptive cutting procedure.

In accordance with one aspect of the present invention, a surgicalapparatus for inserting a cannula through tissue defining a wall of abody cavity comprises a hollow axially elongated tube having a proximalend and a distal end. A substantially solid optically clear tip has adistal cutting end and a proximal base end which is secured to thedistal end of the tube. A cutting element is disposed at the distal endof the tip for cutting the tissue for insertion of a cannula through thetissue into the body cavity. For electrosurgical cutting, the cuttingelement may comprise at least one electrode disposed at the distalcutting end of the tip. For this embodiment, at least one electricalconductor extending from the proximal end of the tube to the distal endof the tube is connected to the at least one electrode for conductinghigh frequency energy thereto.

The distal cutting end of the substantially solid optically clear tipcan be formed by a pair of opposing angularly oriented surfaces whichconverge to a line at the distal cutting end of the tip. For thisembodiment of the tip, the at least one electrode is disposed along theline of the tip. The tip can include an axial bore extending from itsproximal base end to its distal cutting end with a viewing rodpositioned within the axial bore. The viewing rod has a proximal enddefining a viewing port at the proximal base end of the tip and a distalend defining a window at the distal cutting end of the tip forcollecting light which is carried to the viewing port by the viewingrod. The window at the distal end of the viewing rod may comprise a pairof opposing angularly oriented surfaces which converge to a line at thedistal end of the viewing rod, which line is substantially parallel tothe line defined by the tip. Preferably, the distal end of the viewingrod distally extends beyond the distal cutting end of the substantiallysolid optically clear tip.

If an axial bore/viewing rod is provided in the tip, the at least oneelectrode comprises two electrodes extending on either side of the axialbore along the line of the tip and the at least one electrical conductorcomprises two electrical conductors adapted at the proximal end of thetube for connection to a source of radio frequency energy. A first oneof the two electrical conductors is connected to a first one of the twoelectrodes and a second one of the two electrical conductors isconnected to a second one of the two electrodes. The tube may be made ofpolymeric material with the two electrical conductors embedded ingenerally diametrically opposite outer sections of the tube tofacilitate insertion of an endoscope into the tube and to help ensureinsulation of the conductors from the endoscope.

In accordance with another aspect of the present invention a surgicalapparatus assembly for penetrating a tissue wall of a body cavity toprovide an operative channel through the tissue wall into the bodycavity comprises a cannula having a distal end and a proximal end, andbeing adapted for insertion through the tissue wall with the distal endinside the body cavity and the proximal end outside the body cavity. Anobturator is removably disposed in the cannula and comprises: a hollowaxially elongated tube having a proximal end and a distal end; asubstantially solid optically clear tip, the tip having a distal cuttingend and a proximal base end secured to the distal end of the tube; and,a cutting element disposed at the distal end of the tip for cutting thetissue wall for insertion of the cannula through the tissue wall intothe body cavity. With this assembly, the distal end of the obturator andthe distal end of the cannula can be advanced through a tissue wall andthe obturator can be removed from the cannula leaving the cannulainserted through the tissue wall.

In accordance with yet another aspect of the present invention, asurgical apparatus for inserting a cannula through tissue defining awall of a body cavity comprises a hollow axially elongated tube having aproximal end and a distal end. A substantially solid optically clear tiphas a distal cutting end and a proximal base end with the proximal baseend secured to the distal end of the tube. The tip comprises a firstpole and a second pole located proximally of the first pole andelectrically isolated therefrom by an insulator. The first and secondpoles receive bipolar energy for cutting the tissue for insertion of acannula through the tissue into the body cavity. Preferably, the firstpole, the insulator and the second pole form a tapered tip having asubstantially acute tip angle.

It is thus an object of the present invention to provide an improvedtrocar having a trocar obturator including a hollow tube having asubstantially solid, optically clear tip attached thereto is used toinsert a cannula through a tissue wall of a body cavity; to provide animproved trocar having a trocar obturator including a hollow tube havinga substantially solid, optically clear tip attached thereto, the distalcutting end of the tip formed by a pair of opposing angularly orientedsurfaces which converge to a line having a cutting element, preferablyat least one electrode, disposed therealong at the distal end of thetip; to provide an improved trocar having a trocar obturator including ahollow tube having a substantially solid, optically clear tip attachedthereto and having an axial bore extending from its proximal end to itsdistal end with a viewing rod positioned within the bore; and, toprovide an improved trocar having a trocar obturator including a hollowtube having a substantially solid, optically clear tip attached theretoand having an axial bore extending from its proximal end to its distalend with a viewing rod positioned within the bore and extending from theproximal end of the tip to beyond the distal end of the tip.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative embodiment of a rftrocar including the invention of the present application with the rftrocar having an endoscope inserted therein for viewing purposes;

FIG. 2 is an exploded view of the rf trocar of FIG. 1 showing the trocarcannula and associated handle portion at its proximal end, the rf trocarobturator and associated handle portion at its proximal end, and theendoscope;

FIG. 3 is an exploded view of a substantially solid optically clear tipwhich is secured to a distal end of a hollow axially elongated tube toform the distal end of the rf trocar obturator of the trocar of FIGS. 1and 2;

FIGS. 4, 5 and 6 are front, side and end views of the substantiallysolid clear tip shown in FIGS. 1-3;

FIG. 7 is an end view of one alternate embodiment of the substantiallysolid optically clear tip shown in FIGS. 1-6 without an axially orientedviewing rod;

FIG. 8 is an exploded view of another alternate embodiment of asubstantially solid optically clear tip for use with bipolar rf energy;

FIGS. 9, 10 and 11 are front, side and end views of the substantiallysolid optically clear bipolar rf tip shown in FIG. 8; and,

FIG. 12 is an end view of an alternate embodiment of the substantiallysolid optically clear tip shown in FIGS. 8-11 wherein an axiallyoriented viewing rod has been added in a manner similar to the tipembodiments of FIGS. 1-7.

DETAILED DESCRIPTION OF THE INVENTION

A trocar 100 in accordance with the present invention is shown in FIGS.1 and 2. Various aspects of the overall structure of the trocar 100which are not directly related to the invention of the presentapplication will not be described in detail herein. For additionalinformation relating to these details, the reader is referred to U.S.Pat. No. 5,256,149 which is assigned to the assignee of the presentapplication and is incorporated herein by reference.

The trocar 100 has a trocar cannula 102 and a trocar obturator 104. Inthe illustrated embodiment, the trocar obturator 104 can be seen throughthe cannula 102. The proximal end 102a of the trocar cannula 102 issecured to an associated housing portion 106 and the proximal end 104aof the trocar obturator 104 is secured to an associated housing portion108, see FIG. 2.

The distal end 104b of the trocar obturator 104 is inserted into theproximal end 102a of the trocar cannula 102 through the housing portion106 until it extends beyond the distal end 102b of the trocar cannula102 and the housing portions 106 and 108 are interlocked to one anotheras shown in FIG. 1. An appropriately sized endoscope 110 is insertedinto the trocar 100 for viewing the insertion of the trocar 100 as willbecome apparent. The endoscope 110 is selectively secured into thetrocar 100 by means of a locking cam mechanism 112 secured to the trocarobturator 104 external to the housing portion 108.

In the illustrated embodiment, the trocar obturator 104 comprises ahollow axially elongated tube 114 having a proximal end 114a and adistal end 114b. The tube 114 is terminated by a substantially solidoptically clear tip 116 having a distal cutting end 116a and a proximalbase end 116b secured to the distal end 114b of the tube 114. A cuttingelement is disposed at the distal cutting end 116a of the tip 116 forcutting tissue 118 for insertion of the cannula 102 through the tissue118 into a body cavity 120, see FIG. 5. The tip 116 is made of anoptically clear polymer such as acrylic, polycarbonate or otherappropriate material.

For an rf trocar, the cutting element comprises at least one electrodedisposed at the distal cutting end 116a of the tip 116. At least oneelectrical conductor extends from the proximal end 114a of the tube 114to the distal end 116b of the tube 116 and is connected to theelectrode(s) for conducting high frequency energy thereto forelectrosurgically cutting the tissue 118 to insert the cannula 102through the tissue into the body cavity 120.

In the embodiment of the invention shown in FIGS. 1-7, two electrodes122, 124 are sandwiched between two substantially solid optically clearbody halves 116', 116" as best shown in FIG. 3. In the illustratedembodiment, the electrodes 122, 124 are made from surgical stainlesssteel having a thickness of approximately 0.005 inches. While theelectrode or electrodes can be shaped differently than illustrated,preferably the electrode or electrodes are formed to have a sufficientmass to sink heat generated by the tissue cutting process.

Two electrical conductors 126, 128 are connected respectively to the twoelectrodes 122, 124 within recesses 130 in the sides of the body halves116', 116". Preferably, the tube 114 is made of polymeric material andthe conductors 126, 128 are embedded in generally diametrically oppositeouter sections of the surface of the tube 114. By embedding theconductors 126, 128 into the outer surface of the tube 114, the innersurface of the tube 114 remains smooth to facilitate insertion of theendoscope 110 into the tube 114 and the conductors 126, 128 are betterinsulated from the endoscope 110. While two clear body halves 116' and116" are illustrated as being glued, welded or otherwise secured to theremaining structure to form the tip 116, it should be apparent that thetip 116 can be molded or otherwise formed as a single body.

The trocar obturator 104 including the tip 116 is designed to beoperated as a monopolar rf trocar such that both of the electricalconductors 126, 128 are connected together at the proximal end 104a ofthe obturator 104. The conductors 126, 128 are then routed outside thehousing portion 108 of the trocar obturator 104 via an electricalconductor 131 which is terminated in an appropriate connector 131' forconnection to an appropriate source of rf energy.

In the embodiment of the invention illustrated in FIGS. 1-6, thesubstantially solid optically clear tip 116 includes an axial bore 132extending from its proximal base end 116b to its distal cutting end116a. A viewing rod 134 is positioned within the axial bore 132, theviewing rod 134 having a proximal end 134a defining a viewing port atthe proximal base end 116b of the tip 116 and a distal end 134b defininga window at the distal cutting end 116a of the tip 116 for collectinglight which is carried to the viewing port 134a by the viewing rod 134.The viewing rod is made of an optically clear polymer such as acrylic orpolycarbonate or other appropriate material. In the illustratedembodiment, the viewing rod has a diameter of approximately 0.100 inchesfor a trocar obturator having a diameter of approximately 0.500 inches.Of course, other relative dimensions can be used in the invention of thepresent application.

In the embodiments of FIGS. 1-7, the substantially solid optically cleartip 116 is formed by a pair of opposing angularly oriented surfaces 136,138 which converge to a line 140 at the distal cutting end 116a of thetip 116, the electrode(s) being disposed along the line 140 of the tip116. The opposing angularly oriented surfaces 136, 138 define viewingfaces for the tip 116 such that a surgeon inserting the trocar 100 intoa patient can observe the tissue 118 as the trocar 100 is insertedtherethrough by means of the endoscope 110. In this way the surgeon canoptically steer the trocar 100 and thereby reduce the risk of possibledamage to vessels and other structures within and beyond the tissue 118.

In the embodiments of FIGS. 1-6, the viewing rod 134 further assists thesurgeon by permitting the surgeon to see a short distance beyond thetissue then being penetrated by the rf energy by means of the viewingport 134a of the viewing rod 134. Like the proximal base end 116b if thetip 116, the viewing port 134a is viewed by means of the endoscope 110which is inserted through the hollow tube 114 to substantially abut theproximal base end 116b of the tip 116 and the viewing port 134a of theviewing rod 134.

The distal end 134b of the viewing rod 134 comprises a pair of opposingangularly oriented surfaces 142, 144 which converge to a line 146 at thedistal end 134b of the viewing rod 134. The line 146 at the distal endof the viewing rod 134 and the line 140 at the distal cutting end 116aof the substantially solid optically clear tip 116 are substantiallyparallel to one another. Preferably, the distal end 134b of the viewingrod 134 distally extends beyond the distal cutting end 116a of thesubstantially solid optically clear tip 116.

FIG. 6 shows an end view of the substantially solid optically clear tip116 looking down the tube 114 which is sectioned. The semicircularregions 116 up transmit to the endoscope what is passing by the viewingfaces defined by the opposing angularly oriented surfaces 136, 138. In asimilar manner, the viewing port 134a of the viewing rod 134 transmitsto the endoscope 110 what is passing by viewing faces defined by thepair of opposing angularly oriented surfaces 142, 144 of the viewing rod134. In this way, the surgeon can view what is slightly ahead of thecutting end 116a of the tip 116 and thereby reduce the risk of possibledamage to vessels, organs and the like not only within the tissue beingpenetrated but also within the body cavity to which the surgeon isgaining entry.

FIG. 7 is an end view of an embodiment of a tip 116' which does notinclude the viewing rod 134. In this embodiment, the surgeon is able toview tissue passing by the viewing faces defined by opposing angularlyoriented surfaces of the tip 116' by means of the endoscope 110substantially abutting the semicircular regions 116 up' of the tip 116'.

While a variety of trocar obturators will be suggested to those skilledin the art in view of the foregoing description, two other alternateembodiments of substantially solid optically clear tips for use withbipolar rf energy will now be described with reference to FIGS. 8-12.The basic structure of the trocar obturator tips shown in these figuresis the subject of a pending U.S. patent application, Ser. No.08/140,353, filed on Oct. 20, 1993, and entitled Electrosurgical Trocarwhich is assigned to the same assignee as the present application and isincorporated herein by reference.

In the embodiment of the invention shown in FIGS. 8-11, a single thincutting element 150 having a thickness of approximately 0.005 inchesdefines a tip which acts as a first pole of the bipolar trocarobturator. The cutting element 150 extends distally from insulationmaterial, such as Ultem™, between which it is sandwiched or surrounded.In the illustrated embodiment, the insulation material comprises twoinsulating plates 152. The cutting element 150 is blunt to protectvessels and other structures within a cavity into which it is inserted.Two return electrodes 154 are provided on opposite sides of theinsulating plates 152. The layered structure defined by the returnelectrodes 154, the insulating plates 152 and the cutting element 150 issecured within a cavity 156 defined in the distal end of a substantiallysolid optically clear tip 158 which is shaped substantially the same asthe tip 116.

In particular, the optically clear tip 158 is formed by a pair ofopposing angularly oriented surfaces 160, 162 which would converge to aline substantially including the cutting element 150. The opposingangularly oriented surfaces 160, 162 define viewing faces for the tip158 such that a surgeon inserting the trocar 100 into a patient canobserve the tissue 118 as a trocar including a trocar obturatorincluding the tip 158 is inserted therethrough by means of the endoscope110. In this way the surgeon can optically steer the trocar and therebyreduce the risk of possible damage to vessels and other structureswithin and beyond the tissue 118.

The cutting element 150 is connected to a first electrical conductor 164which preferably is extended along and embedded within the outer surfaceof a hollow axially elongated tube, such as the tube 114, as previouslydescribed with reference to the embodiments of FIGS. 1-7. The returnelectrodes 154 are connected to a second electrical conductor 166 whichdivides into electrical conductors 166a and 166b as shown in FIG. 8,with the second electrical conductor 166 also preferably being extendedalong and embedded within the outer surface of a hollow axiallyelongated tube, such as the tube 114, as previously described withreference to the embodiments of FIGS. 1-7. The electrical conductors164, 166 are received within channels 158c running along diametricallyopposed sides of the tip 158.

In the embodiment of FIGS. 8-11, the surgeon is able to view tissuepassing by the viewing faces defined by the opposing angularly orientedsurfaces 160, 162 of the tip 158 by means of the endoscope 110substantially abutting the semicircular regions 158 up of the tip 158,see FIG. 11.

FIG. 12 is an end view of an embodiment of a tip 158' which includes aviewing rod 168 which is inserted into an axial bore 170 thorough thetip 158' in a manner substantially the same as that described aboverelative to the tip 116. In this embodiment, the surgeon is able to viewtissue passing by the viewing faces defined by the opposing angularlyoriented surfaces of the tip 158' by means of the endoscope 110substantially abutting the semicircular regions 158 up' of the tip 158'.In addition, the surgeon can view tissue slightly ahead of the cuttingelement 150 by means of a viewing port defined by the proximal end ofthe viewing rod 168 substantially as described above relative to theviewing rod 134.

Having thus described the invention of the present application in detailand by reference to preferred embodiments thereof, it will be apparentthat modifications and variations are possible without departing fromthe scope of the invention defined in the appended claims.

What is claimed is:
 1. A surgical apparatus for inserting a cannulathrough tissue defining a wall of a body cavity, said surgical apparatuscomprising:a hollow axially elongated tube having a proximal end and adistal end; a substantially solid optically clear tip, said tip having adistal cutting end and a proximal base end secured to said distal end ofsaid tube and including an axial bore extending from its proximal baseend to its distal cutting end; a viewing rod positioned within saidaxial bore of said tip, said viewing rod having a proximal end defininga viewing port at said proximal base end of said tip and a distal enddefining a window at said distal cutting end of said tip for collectinglight which is carried to said viewing port by said viewing rod; and acutting element disposed at the distal end of said tip for cutting saidtissue for insertion of a cannula through said tissue into said bodycavity, said cutting element comprising:at least one electrode disposedat said distal cutting end of said tip; and at least one electricalconductor extending from said proximal end of said tube to said distalend of said tube, said at least one electrical conductor being connectedto said at least one electrode for conducting high frequency energythereto for electrosurgically cutting said tissue to insert a cannulathrough said tissue into said body cavity.
 2. A surgical apparatus asclaimed in claim 1 wherein said at least one electrode comprises twoelectrodes extending on either side of said axial bore along said lineof said tip and said at least one electrical conductor comprises twoelectrical conductors adapted at said proximal end of said tube forconnection to a source of radio frequency energy, a first one of saidtwo electrical conductors connected to a first one of said twoelectrodes and a second one of said two electrical conductors connectedto a second one of said two electrodes.
 3. A surgical apparatus asclaimed in claim 1 wherein the distal cutting end of said substantiallysolid optically clear tip is formed by a pair of opposing angularlyoriented surfaces which converge to a line at said distal cutting end ofsaid tip, said at least one electrode being disposed along said line ofsaid tip.
 4. A surgical apparatus as claimed in claim 2 wherein saidwindow at said distal end of said viewing rod comprises a pair ofopposing angularly oriented surfaces which converge to a line at saiddistal end of said viewing rod.
 5. A surgical apparatus as claimed inclaim 4 wherein said line at said distal end of said viewing rod andsaid line at said distal end of said distal cutting end of saidsubstantially solid optically clear tip are substantially parallel toone another.
 6. A surgical apparatus as claimed in claim 5 wherein saiddistal end of said viewing rod distally extends beyond said distalcutting end of said substantially solid optically clear tip.
 7. Asurgical apparatus as claimed in claim 6 wherein said tube is made ofpolymeric material and said two electrical conductors are embedded ingenerally diametrically opposite outer sections of said tube tofacilitate insertion of an endoscope into said tube and to insulate saidtwo electrical conductors from said endoscope.
 8. A surgical apparatusassembly for penetrating a tissue wall of a body cavity to provide anoperative channel through said tissue wall into said body cavity, saidassembly comprising:a cannula having a distal end and a proximal end,and being adapted for insertion through said tissue wall with saiddistal end inside said body cavity and said proximal end outside saidbody cavity; and an obturator removably disposed in said cannula andcomprising:a hollow axially elongated tube having a proximal end and adistal end; a substantially solid optically clear tip, said tip having adistal cutting end and a proximal base end secured to said distal end ofsaid tube and including an axial bore extending from its proximal baseend to its distal cutting end; and a cutting element disposed at thedistal end of said tip for cutting said tissue wall for insertion ofsaid cannula through said tissue wall into said body cavity, saidcutting element comprising at least one electrode disposed at saiddistal cutting end of said tip, and at least one electrical conductorextending from said proximal end of said tube to said distal end of saidtube, said at least one electrical conductor being connected to said atleast one electrode for conducting high frequency energy thereto forelectrosurgically cutting said tissue wall to insert said cannulathrough said tissue wall into said body cavity; and a viewing rodpositioned within said axial bore of said tip, said viewing rod having aproximal end defining a viewing port at said proximal base end of saidtip and a distal end defining a window at said distal cutting end ofsaid tip for collecting light which is carried to said viewing port bysaid viewing rod; whereby said distal end of said obturator and thedistal end of said cannula can be advanced through a tissue wall and theobturator can be removed from said cannula leaving said cannula insertedthrough said tissue wall.
 9. A surgical apparatus assembly as claimed inclaim 8 wherein said at least one electrode comprises two electrodesextending on either side of said axial bore along said line of said tipand said at least one electrical conductor comprises two electricalconductors adapted at said proximal end of said tube for connection to asource of radio frequency energy, a first one of said two electricalconductors connected to a first one of said two electrodes and a secondone of said two electrical conductors connected to a second one of saidtwo electrodes.
 10. A surgical apparatus assembly as claimed in claim 8wherein the distal cutting end of said substantially solid opticallyclear tip is formed by a pair of opposing angularly oriented surfaceswhich converge to a line at said distal cutting end of said tip, said atleast one electrode being disposed along said line of said tip.
 11. Asurgical apparatus assembly as claimed in claim 9 wherein said window atsaid distal end of said viewing rod comprises a pair of opposingangularly oriented surfaces which converge to a line at said distal endof said viewing rod.
 12. A surgical apparatus assembly as claimed inclaim 11 wherein said line at said distal end of said viewing rod andsaid line at said distal end of said distal cutting end of saidsubstantially solid optically clear tip are substantially parallel toone another.
 13. A surgical apparatus assembly as claimed in claim 12wherein said distal end of said viewing rod distally extends beyond saiddistal cutting end of said substantially solid optically clear tip. 14.A surgical apparatus assembly as claimed in claim 12 wherein said tubeis made of polymeric material and said two electrical conductors areembedded in generally diametrically opposite outer sections of said tubeto facilitate insertion of an endoscope into said tube and to insulatesaid two electrical conductors from said endoscope.
 15. A surgicalapparatus for inserting a cannula through tissue defining a wall of abody cavity, said surgical apparatus comprising:a hollow axiallyelongated tube having a proximal end and a distal end; a substantiallysolid optically clear tip having a distal cutting end and a proximalbase end secured to said distal end of said tube, an axial boreextending from its proximal base end to its distal cutting end, andcomprising:a first pole; and a second pole located proximally of saidfirst pole and electrically isolated therefrom by an insulator, saidfirst and second poles receiving bipolar energy for cutting said tissuefor insertion of a cannula through said tissue into said body cavity; afirst electrical conductor extending from said proximal end of said tubeto said distal end of said tube, said first electrical conductor beingconnected to said first pole; a second electrical conductor extendingfrom said proximal end of said tube to said distal end of said tube,said second electrical conductor being connected to said second pole,said first and second electrical conductors conducting high frequencyenergy to said first and second poles for electrosurgically cutting saidtissue to insert a cannula through said tissue into said body cavity;and a viewing rod positioned within said axial bore of said tip, saidviewing rod having a proximal end defining a viewing port at saidproximal base end of said tip and a distal end defining a window at saiddistal cutting end of said tip for collecting light which is carried tosaid viewing port by said viewing rod.
 16. A surgical apparatus asclaimed in claim 15 wherein said window at said distal end of saidviewing rod comprises a pair of opposing angularly oriented surfaceswhich converge to a line at said distal end of said viewing rod.
 17. Asurgical apparatus as claimed in claim 15 wherein said first pole, saidinsulator and said second pole form a tapered tip having a substantiallyacute tip angle.
 18. A surgical apparatus as claimed in claim 16 whereinsaid distal end of said viewing rod distally extends beyond said distalcutting end of said substantially solid optically clear tip.